Feeding in Birds: Thriving in Terrestrial, Aquatic, and Aerial Niches

Rico‐Guevara, Alejandro; Sustaita, Diego; Gussekloo, Sander W. S.; Olsen, Aaron M.; Bright, Jen A.; Corbin, Clay E.; Dudley, Robert

doi:10.1007/978-3-030-13739-7_17

Cited by 19 publications

(27 citation statements)

References 254 publications

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“…Flamingos are noteworthy not only for long legs and balancing on one foot, but also for their feeding habit, which requires them to lower and swing their head through the water while keeping their torso stable. Spoonbills exhibit a similar behavior (Rico-Guevara et al, 2019), and it would be interesting to compare their LSO morphology with that of flamingos. Perching and balancing on one foot may be the types of balance-intensive behaviors partially enabled by exaggerated LSO morphology.…”

Section: Resultsmentioning

confidence: 99%

The balance hypothesis for the avian lumbosacral organ and an exploration of its morphological variation

Stanchak

French

Perkel

et al. 2020

Preprint

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Birds (Aves) exhibit exceptional and diverse locomotor behaviors, including the exquisite ability to balance on two feet. How birds so precisely control their movements may be partly explained by a set of intriguing modifications in their lower spine. These modifications are collectively known as the lumbosacral organ (LSO) and are found in the fused lumbosacral vertebrae called the synsacrum. They include a set of transverse canal-like recesses in the synsacrum that align with lateral lobes of the spinal cord, as well as a dorsal groove in the spinal cord that houses an egg-shaped glycogen body. Based on compelling but primarily observational data, the most recent functional hypotheses for the LSO consider it to be a secondary balance organ, in which the transverse canals are analogous to the semicircular canals of the inner ear. If correct, this hypothesis would reshape our understanding of avian locomotion, yet the LSO has been largely overlooked in the recent literature. Here, we review the current evidence for this hypothesis and then explore a possible relationship between the LSO and balance-intensive locomotor ecologies.Our comparative morphological dataset consists of micro-computed tomography (μ-CT) scans of synsacra from ecologically diverse species. We find that birds that perch tend to have more prominent transverse canals, suggesting that the LSO is useful for balance-intensive behaviors.We then identify the crucial outstanding questions about LSO structure and function. The LSO may be a key innovation that allows independent but coordinated motion of the head and the body, and a full understanding of its function and evolution will require multiple interdisciplinary research efforts. Jargon-FreeBirds have an uncanny ability to move their heads independently of their bodies. They can keep their heads remarkably still to focus on their prey while twisting in flight or perched on a bouncing branch. How are they able to do this? Like us, birds have balance organs in their inner ears that act like gyroscopes. Surprisingly, birds may have an additional balance organ known as the "lumbosacral organ" in their spine, right above their legs, which might help them sense the movement of their body separately from their head. This second balance organ may have played a very important role in bird evolution and how birds move, but it has seldom been considered in recent scientific studies. This intriguing hypothesis is based in part on a series of fluid-filled, canal-like recesses in the bone surrounding the spinal cord, which resemble the semicircular canals of the inner ear. We looked for evidence of these canal-like recesses in many different bird species, and we found it in every bird we examined. We also found that birds that perch often have deeper recesses than birds that do not perch, suggesting these canals help maintain balance. This paper presents those findings, reviews the existing research, and identifies some key questions that need to be asked to advance our understanding of this fascinating and ...

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Section: Resultsmentioning

confidence: 99%

The balance hypothesis for the avian lumbosacral organ and an exploration of its morphological variation

Stanchak

French

Perkel

et al. 2020

Preprint

View full text Add to dashboard Cite

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“…The difference between lizards and other reptiles for which drinking has been studied probably relates to the amount of water able to be carried into the mouth by the tongue during each tongue cycle, and to the complexities of tongue action and/or of the anatomy of the oropharyngeal compartments (including their number and positions) involved in water carriage and transport. In lizards such as E. macularius , the fore tongue is only able to collect a small amount of water during each cycle and, as in some birds (Rico‐Guevara et al , ), there is a clear emersion phase related to swallowing.…”

Section: Discussionmentioning

confidence: 99%

“…Water is an essential resource, and most terrestrial vertebrates must drink to compensate for water loss. In many taxa, the tongue is used actively during drinking (Heidweiller, van Loon & Zweers, ; Bels, Goosse & Kardong, ; Kim & Bush, ; Rico‐Guevara et al , ; Bels et al , ). It is, therefore, anticipated that the tongue’s morphology and functional anatomy, and those of associated areas of the buccopharyngeal region, will reflect efficient and effective transfer of water from the environment to the oral chamber and thence to the gut.…”

Section: Introductionmentioning

confidence: 99%

“…It is, therefore, anticipated that the tongue’s morphology and functional anatomy, and those of associated areas of the buccopharyngeal region, will reflect efficient and effective transfer of water from the environment to the oral chamber and thence to the gut. Rarely, however, has the functional relationship between buccolingual morphology and drinking kinematics been explored (Kooloos & Zweers, ; Heidweiller et al , ; Kardong & Haverly, ; Thexton, Crompton & German, ; Wagemans et al , ; German, Crompton, & Thexton, ; Reis et al , ; Crompton & Musinsky, ; Gart et al , ; Houze & Damman, ; Rico‐Guevara et al , ).…”

Section: Introductionmentioning

confidence: 99%

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Mechanics and kinematics of fluid uptake and intraoral transport in the leopard gecko

et al. 2020

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Drinking permits amniote vertebrates to compensate for water loss. Lizards (nonophidian squamates) use their tongue to imbibe water, but for most lizards the tongue is also employed in other activities. To determine how these various demands can be accommodated alongside the tongue's role in drinking, it is necessary to firstly determine the tongue's function in water uptake and intraoral transport in a lizard that does not use this organ for chemoreception or food prehension. We selected the leopard gecko (Eublepharis macularius) for this purpose. We build upon previous morphological observations of the anatomy of its tongue and oral cavity and explore its drinking behaviour through high-speed cinematography and cineradiography. This allows us to follow the movement of radio-opaquely labelled water in association with tongue, jaw and throat movements. The tongue is modified to collect water and to release it into the anterior region of the buccal cavity. Repeated tongue cycles are associated with the shifting of the imbibed water into paired ventrolateral chambers and ultimately to its passage to a single, midline posterior chamber prior to swallowing. Tongue movements, capillarity and pressure changes due to hyolingual movements cause water to be moved posteriorly along specific pathways prior to swallowing, bypassing the airways and dorsal surface of the mid-and hind tongue. In this licking-based lingually driven approach to drinking, only small volumes of water can be gathered at a time, with a drinking bout consisting of 20-30 tongue cycles before emersion and swallowing occur. This mechanism differs from drinking in turtles and snakes, which do not employ licking and may take in larger quantities of water. We advance the hypothesis that all lizards have conserved this pattern of tongue-based water uptake and precisely directed intraoral fluid transport, with specializations for tongue-based food capture and/or lingually based chemoreception being superimposed thereupon.

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“…Flamingos are noteworthy not only for long legs and balancing on one foot, but also for their feeding habit, which requires them to lower and swing their head through the water while keeping their torso stable. Spoonbills exhibit a similar behavior ( Rico-Guevara et al. 2019 ), and it would be interesting to compare their LSO morphology with that of flamingos.…”

Section: Comparative Exploration Of Lso Osteologymentioning

confidence: 99%

The Balance Hypothesis for the Avian Lumbosacral Organ and an Exploration of Its Morphological Variation

Stanchak

French

Perkel

et al. 2020

Integrative Organismal Biology

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Synopsis Birds (Aves) exhibit exceptional and diverse locomotor behaviors, including the exquisite ability to balance on two feet. How birds so precisely control their movements may be partly explained by a set of intriguing modifications in their lower spine. These modifications are collectively known as the lumbosacral organ (LSO) and are found in the fused lumbosacral vertebrae called the synsacrum. They include a set of transverse canal-like recesses in the synsacrum that align with lateral lobes of the spinal cord, as well as a dorsal groove in the spinal cord that houses an egg-shaped glycogen body. Based on compelling but primarily observational data, the most recent functional hypotheses for the LSO consider it to be a secondary balance organ, in which the transverse canals are analogous to the semicircular canals of the inner ear. If correct, this hypothesis would reshape our understanding of avian locomotion, yet the LSO has been largely overlooked in the recent literature. Here, we review the current evidence for this hypothesis and then explore a possible relationship between the LSO and balance-intensive locomotor ecologies. Our comparative morphological dataset consists of micro-computed tomography (μ-CT) scans of synsacra from ecologically diverse species. We find that birds that perch tend to have more prominent transverse canals, suggesting that the LSO is useful for balance-intensive behaviors. We then identify the crucial outstanding questions about LSO structure and function. The LSO may be a key innovation that allows independent but coordinated motion of the head and the body, and a full understanding of its function and evolution will require multiple interdisciplinary research efforts.

show abstract

Feeding in Birds: Thriving in Terrestrial, Aquatic, and Aerial Niches

Cited by 19 publications

References 254 publications

The balance hypothesis for the avian lumbosacral organ and an exploration of its morphological variation

The balance hypothesis for the avian lumbosacral organ and an exploration of its morphological variation

Mechanics and kinematics of fluid uptake and intraoral transport in the leopard gecko

The Balance Hypothesis for the Avian Lumbosacral Organ and an Exploration of Its Morphological Variation

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